255 Viton O-Ring 75A Durometer 5-5/8in ID 5-7/8in OD - Durable Seal

In this review the 255 Viton O-ring is judged as a straightforward replacement seal for demanding applications that need chemical and heat resistance. The bottom line: this pack of ten o-rings is best for technicians and hobbyists who need a reliable, high-temperature sealing solution because it combines a proven fluorocarbon compound with the common AS568A sizing standard. The reviewer found the o-rings offer consistent dimensions, a firm but flexible 75A durometer feel, and compatibility with fuels and many solvents that typical nitrile rings cannot tolerate.

Key Features

• Material: Viton fluorocarbon elastomer provides superior resistance to heat, fuels, and many chemicals compared with general-purpose rubbers.
• Temperature range: Rated from -15 degrees F to 400 degrees F, so the o-ring can be used in both low-temperature storage and high-heat service environments.
• Size and standard: 5-5/8in ID and 5-7/8in OD in AS568A 255 size, making it a drop-in replacement for equipment that follows aerospace and industrial sizing.
• Durometer: 75A hardness balances resistance to penetration with enough elasticity to form reliable seals between cylindrical surfaces.
• Chemical compatibility: Suitable for non-flammable hydraulic fuels, silicone oils, aromatic and aliphatic hydrocarbons, and many chlorinated solvents encountered in field service.

Who It's For

This kit is aimed at maintenance professionals, plumbing and hydraulic technicians, firearms and suppressor owners doing seal replacement, and anyone needing a high-heat, fuel-resistant o-ring in a common AS568A size. The pack size of ten is useful for repeat maintenance or keeping spares on hand.

Those who should look elsewhere include users who need resistance to low molecular weight organic acids, ammonia, strong alkalis or glycol-based brake fluids, or who require very soft, low durometer seals; in those cases a different elastomer or a softer durometer would be more appropriate.

Pros & Cons

Pros

• Excellent chemical and fuel resistance for demanding industrial and automotive uses.
• Wide temperature capability from -15 degrees F to 400 degrees F for versatility in many applications.
• Consistent sizing to AS568A 255 standard makes replacements easy to source and install.
• Pack of ten offers good value and spare parts for maintenance routines.

Cons

• Not compatible with ammonia, strong alkalis, some brake fluids, and certain organic acids, so it is not universal for all fluids.
• 75A hardness may be firmer than desired for some delicate sealing interfaces that require softer material.

Specifications

Material	Viton (fluorocarbon elastomer)
Color	Black
Inner diameter	5-5/8 in
Outer diameter	5-7/8 in
Cross-section (width)	1/8 in
Durometer	75A
Temperature range	-15 degrees F to 400 degrees F

Our Verdict

The 255 Viton O-ring pack is a practical choice for professionals and enthusiasts who need a durable, heat- and fuel-resistant seal in an AS568A size. It delivers consistent fit and good chemical compatibility for most fuels and hydrocarbon solvents, and the pack of ten represents sound value for routine maintenance and replacements.

Frequently Asked Questions

Can this o-ring handle gasoline and common fuels?
Yes; Viton is compatible with many fuels and aromatic or aliphatic hydrocarbons, making it suitable for fuel system seals in appropriate applications.

Is the durometer too hard for tight seals?
The 75A hardness offers a balance of resistance and elasticity; it works well for cylindrical overlaps but may be firmer than desired for very delicate or low-pressure seals.

Will it resist high heat environments?
Yes; it is rated up to 400 degrees F, which covers many high-temperature service conditions where elastomer seals are acceptable.